| 摘要 |
<p>Disclosed is an alkaline immersion tin coating composition comprised of a source of tin ions and an effective amount of a sludge control agent that is an organic chelating composition, preferably a polyamine. The tin coating composition is phosphate-free, fluoride ion-free and cyanide-free. Preferably, the coating composition contains organic polyhydroxy materials. The invention is also concerned with a method for coating metallic substrates, in particular, aluminum and aluminum alloy containing substrates and is further comprised of a make up tin concentrate coating composition. The object of the present invention is to provide a good tin coating with good adhesion and a decrease in sludge formation at alkaline pH.</p> |
